Recycled fiber and recycled fiber molding

Abstract

The present invention aims to provide recycled fibers having a low dirt content and excellent appearance and strength properties derived from sanitary products. Recycled fibers having a superabsorbent polymer (SAP) content of less than 10% obtained by subjecting a sanitary product containing a cellulose pulp to a recycling process per se have good appearance, and moldings prepared by using the recycled fibers also have excellent appearance and strength properties. Further, the recycled fibers preferably have a dirt area fraction of 50,000 mm 2 /m 2 or less when determined by a staining assay using cobalt (II) chloride hexahydrate, and a Canadian standard freeness of 600 ml or more.

1 . A recycled fiber obtained by subjecting a sanitary product containing a cellulose pulp to a recycling process, which has a superabsorbent polymer (SAP) content of less than 5%. 
     
     
         2 . The recycled fiber of  claim 1 , which has a dirt area fraction of 50,000 mm 2 /m 2  or less when determined by a staining assay using cobalt (II) chloride hexahydrate on a handsheet having a basis weight of 60 g/m 2  prepared according to JIS P 8209. 
     
     
         3 . The recycled fiber of  claim 1 , which has a dirt area fraction of 200 mm 2 /m 2  or less when determined by a dirt assay on a handsheet having a basis weight of 60 g/m 2  prepared according to JIS P 8209. 
     
     
         4 . The recycled fiber of  claim 1 , which has a Canadian standard freeness of 600 ml or more when determined according to JIS P 8121:1995. 
     
     
         5 . The recycled fiber of  claim 1 , which has a length weighted average fiber length of 0.7 mm or more. 
     
     
         6 . The recycled fiber of  claim 1 , which has a superabsorbent polymer content of 1% or less. 
     
     
         7 . The recycled fiber of  claim 1 , which has a dirt area fraction of 1,000 mm 2 /m 2  or less when determined by a staining assay using cobalt (II) chloride hexahydrate on a handsheet having a basis weight of 60 g/m 2  prepared according to JIS P 8209. 
     
     
         8 . The recycled fiber of  claim 1  for use in construction materials, paperboards, cushioning materials or molded products. 
     
     
         9 . The recycled fiber of  claim 6  for use in sanitary products, fluff pulps, writing and printing papers or tissue papers. 
     
     
         10 . A slurry comprising the recycled fiber of  claim 1 . 
     
     
         11 . A wet pulp comprising the recycled fiber of  claim 1 . 
     
     
         12 . A dry pulp comprising the recycled fiber of  claim 1 . 
     
     
         13 . A recycled fiber molding comprising a recycled fiber obtained by subjecting a sanitary product containing a cellulose pulp to a recycling process, which has a superabsorbent polymer (SAP) content of less than 5%. 
     
     
         14 . A process for preparing the recycled fiber of  claim 1 , comprising at least the steps of disintegrating a used sanitary product and dispersing it in water, and separating and recovering fibers and SAPs contained in the sanitary product, characterized in that the step of disintegrating a sanitary product and dispersing it in water comprises adding a bleaching/microbicidal agent, a crosslinking agent and an acidic agent as additives. 
     
     
         15 . The process of  claim 14 , wherein the step of disintegrating a sanitary product and dispersing it in water comprises disintegration at a consistency of 3 to 20% in the presence of sodium hypochlorite as a bleaching/microbicidal agent and calcium chloride as a crosslinking agent, followed by dilution to a consistency of 2% or less and then adding an acidic agent to adjust the pH at 4.5 to 5.5, and also comprises heating at one or more points of the step; and that the separation/recovery step comprises using a cascade separator or feed forward separator having two or more stages. 
     
     
         16 . A process for preparing the recycled fiber of  claim 1 , comprising at least the steps of disintegrating a sanitary product and dispersing it in water, and separating and recovering fibers and SAPs contained in the sanitary product, characterized in that the step of disintegrating a sanitary product and dispersing it in water comprises adding a bleaching/microbicidal agent, a crosslinking agent and an acidic agent as additives.